This is a prospective, randomized, comparative trial of two months of rifampicin (Rif) plus pyrazinamide (PZA) versus twelve months of isoniazid (INH) for the prevention of tuberculosis in persons dually infected with HIV and Mycobacterium Tuberculosis (Mtb). It will also evaluate and compare the safety and efficacy of two regimens in the prevention of the reactivation of tuberculosis. (ACTG 177).